Loud speaker system



March 8, 1960 L. J. PATLA ET AL 2,927,657

LOUD SPEAKER SYSTEM Filed Jan. 29, 1958 INVENTORS ga ma 1 a. BY

' 9, orzs LOUD SPEAKER SYSTEM Louis J. Patla and Donald. L. Patla, Lake Geneva, Wis. Application January 29, 1958, Serial No. 711,976

2 Claims. 01. 181-31) This invention relates to a loud speaker system and in particular to a loud speaker system employing multiple speakers. It is an object of the invention to provide an improved loud speaker system of this character.

In high fidelity sound reproducing systems it is a prime objective that sound be reproduced such that as nearly as possible it cannot be distinguished from the original sound. One important weakness of many sound reproducing systems is that the sound reproduced thereby has a much more pronounced directional characteristic than the original sound. This pronounced directional characteristic of reproduced sound is objectionable not only of'itself but also in that a listener in one position in the listening area frequency experiences substantially differ- .ent sensation than a listener at another position. A speaker system constructed in accordance with the present invention reduces the directional characteristic which is United States Patent-D Sound waves as they are originally produced by a ous different directions depending upon the position in which the stringed instruments is held. Normally in the reproduction of music, all of these sound waves are beamed directly forward by one or more loud speakers, the result being an artificial effect which is not truly characteristic of the musicas it was originally produced and which is readily distinguishable .from the original music on this account. Aloud speaker system constructed in accordance with the present invention also overcomes this. weakness of existing sound reproducing systems.

Accordingly, it is another object of the invention to provide an improved loud speaker system which propagates sound in such a manner that its directional characteristic closely resembles that of the original sound.

It is a further object of the invention to provide an improved loud speaker system which propagates reproduced sound waves in the same directions as the original sound waves were propagated by various musical instruments.

It is a still further object of the invention to provide an improved loud speaker system having various of the advantages recited above while being economical to manufacture.

This invention, together with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the drawings, in which like parts are designated by like reference numerals:

Figure 1 is a front view of a loud speaker system illustrating one embodiment of the invention; and

A 2,927,657 Patented Mar. 8, 1960 Figure 2 is a side elevation, partially broken away, of the same loud speaker system.

The present invention is most effective when it is employed in a multiple speaker system, that is, one' in which the audible range of frequencies is divided, with a low frequency speaker handling the low frequency range and a high frequency speaker handling the higher range. The illustrated embodiment of the invention shows three speakers handling differing ranges of frequencies but it will be readily understood that the invention is applicable to any speaker system having two or more speakers handling two or more difiering ranges of frequencies.

A low frequency speaker 11, a mid-range speaker 12, and a high frequency speaker 13 may be seen in Figure 1 to be so supported that they propagate sound horizontally. It will be appreciated by those skilled in the art that any speaker will have a very substantial angle of dispersion. Accordingly, where it is stated herein that a speaker propagates sound horizontally, it will be understood that the axis of the cone of the propagated sound is approximately horizontal.

The speakers 11, 12 and 13 may be of any desired form. The low frequency speaker 11 should be of substantial size and should have a reasonably low resonant frequency in order that it may readily reproduce. low tones. The high frequency speaker 13 may be of the cone type or horn type and should be adapted to reproduce frequencies near the top of the audible range. The mid-range speaker 12 may be of conventional form.

For reasons well known in the art, the back side of the low frequency speaker should be boxed in, as by the enclosure 14, The particular enclosure illustrated in the drawing is a base reflex type of enclosure as will readily be recognized by a slot 15 in the front wall thereof, this being characteristic thereof. Since base reflex enclosures are well known in the art and since the particular form of enclosure for the low frequency speaker 11 does not of itself constitute a feature of the present invention, it is not described in detail herein. It is believed to be suflicient for the purpose of describing the present invention to point out that improved performance will be obtained if a suitable form of enclosure is provided for the low frequency speaker 11. Alternative to the illustrated base reflex enclosure, this enclosure might be of the infinite baffie type, the folded horn type, or any suitable form which improves performance of the lowfrequency speaker, all as is well recognized in the art.

The mid-range speaker 12 and the high frequency speaker 13 are also contained in an enclosure 16, this en A bafiie 18 is arranged in a horizontal plane between he enclosures 14 and 16. Three additional speakers 21, 22 and 23 are arranged on the baffie 18 to propagate sound vertically. The speaker 21 is a low frequency speaker and may be identical to the speaker 11. The speakers 22 and 23 are respectively mid-range and high frequency speakers and may be identical to the speakers 12 and 13 respectively.

The enclosures 14 and 16 and the bafiie 18 are preferably secured together by a framework 19 which is substantially open. Preferably this framework 19 is covered by asuitable grill cloth in the interest of improv'edappearance and for protection of the speakers. The grill cloth is preferably of the type generally recommended for covering speaker enclosures, such grill cloths having the characteristic of concealing and protecting the speakers while permitting substantially free passage of sound therethrough. It is preferred that the speaker 21 a large group of musicians.

be substantially unobstructed, that is, that both sides of the cone of this speaker be substantially open to the surrounding space. In fact, one reason for the preferred sloping of the front face of the enclosure 14 is that it permits direct passage of a larger percentage of the sound from the rear surface of the cone of the speaker 21'to the surrounding space than would be permitted if the upper surface of the enclosure 14 extended to the front surface of the overall structure.

It is well established in the art that sound emanating from the rear surface of a speaker cone should be trapped by an enclosure such that it will be absorbed (as in an infinite bathe enclosure) or its phase shifted (as in the case of a base refiex enclosure). Accordingly, the exposure of both surfaces of the cone of the speaker 21 is directly contrary to previous theory regarding the use of. loud speakers. v It has been indicated above that the present invention is particularly applicable to a multiple speaker system wherein the audible range of frequencies is divided between a low frequency speaker and a high frequency speaker. This applies only to the speakers which are arranged to propagate sound horizontally, such as the 1 speakers 11, 12 and 13. More particularly, it makes little difference whether the vertically propagated sound comes from a single speaker or a plurality of speakers whichdivide the audible frequency range between them. If a single speaker is employed in place of the speakers 21, 22 and 23, it should be an extended range speaker of quality, range and power output generally comparable to these qualities of the horizontally propagating speakers. The reason that the horizontally propagated sound should come from at least two speakers in order to take full advantage of the present invention is that a substantially improved effect is obtained when the horizontal plane of the vertically propagating speaker or speakers (the baffle 18) lies intermediate the two horizontally propagating speakers, and particularly when the horizontally propagating low frequency speaker lies below that plane and the horizontally propagating high frequency speaker lies above that plane. This basic arrangement, of itself, creates an effect not previously obtained. The vertical propagation of full range sound in combination with horizontal propagation of sound by a high frequency speaker and a low frequency speaker arranged above and below the source of vertically propagated sound creates an overall effect such that a listener has diificulty in recognizing the source of the sound. The listener is made to feel that he is encompassed by the sound, as in the case of attendance at a performance by More specifically, the listener does not have the feeling that sound is beamed at him as is the case with conventional loud speaker systems.

This basic arrangement also has the characteristic of propagating sound in the same directions as the sound was propagated by the instruments which produced the I original sound. For example, sound propagated vertically low frequency speaker 11, the sound is, nevertheless, propagated vertically, and the result is that a realism is obtained by the speaker system of the present invention which is not obtained by prior art speaker systems.

Where the audible range is to be handled by more than a 4 two speakers, for example, the low frequency speaker, the mid-range speaker, and the high frequency speaker of the illustrated embodiment of the invention, a complete set of these speakers is preferably arranged in one horizontal plane to propagate the sound vertically as in the illustrated embodiment of the invention. The low frequency speaker for propagating the sound horizontally is preferably below that plane while the high frequency speaker, and any mid-range speaker, employed to prop agate sound horizontally are preferably arranged above that plane. The arrangement of the vertically propagating speakers, and particularly the low frequency speaker 21, such that sound from both sides of the cone'passes directly to the listening area is still another feature of the present invention which adds to the performance of the system, contrary to current understanding regarding the enclosing of low frequency reproducers. It will be .apparent that the invention may be varied in its" physical embodiment without departing from the spirit of'the invention, and it is desired, therefore, that the invention be limited only by the scope of 'the appended claims.

The invention having thus been described, what is claimed and desired to be secured by Letters Patent is:

1. A loud speaker system for reproducing sound within a given range of frequencies comprising, a low frequency speaker for reproducing sound in the low frequency portion of said range, an enclosure for said speaker, said enclosure supporting said speaker to propagate sound substantially horizontally, an open framework extending upwardly from said enclosure, a baffle supported by said framework in a generally horizontal plane substantially above the upper surface of said enclosure, a high frequency speaker for reproducing sound in the remaining portion of said range and a second low frequency speaker mounted on said battle for propagating sound vertically, a second high frequency speaker mounted on said framework, a substantial distance above said vertically propagating speakers to propagate sound horizontally.

2. A loud speaker system for reproducing sound within a given range of frequencies comprising, a low frequency speaker for reproducing sound in the low frequency portion of said range, an enclosure for said speaker, said enclosure supporting said speaker to propagate sound substantially horizontally, an open framework extending upwardly from said enclosure, a bathe supported by said framework in a generally horizontal plane substantially above the upper surface of said enclosure, a high frequency speaker for reproducing sound in the remaining portion of said range and mounted on said framework a substantial distance above said bafiie to propagate sound horizontally, and speaker means for reproducing sound over substantially said 'given range of frequencies mounted on said baffle for propagating sound vertically.

References Cited in the file of this patent UNITED STATES PATENTS 1,932,343 Holland Oct. 24, 1933 2,065,367 Evans Dec. 22, 1936 2,217,279 Karns Oct. 8, 1940 2,699,090 Underhill Ian. 11, 1955 1 FOREIGN PATENTS 734,513 Germany June 9, 1943 

